Multiple image optical system



Ox) U l U March 28, 1939. THOMAS MULTIPLE IMAGE OPTICAL SYSTEM FiledJune 30, 1936 4 Shee ts-Sheet 1 INVENTOR.

BY i 6 M ATTORNEYS March 28, 1939. R. THOMAS 2,152,224

MULTIPLE IMAGE OPTICAL SYSTEM Filed. June 30, 1936 4 Sheets-Sheet 2March 28, 1939. R, TH MA 2,152,224

MULTIPLE IMAGE OPTICAL SYSTEM Filed June 50, 1936 4 Sheets-Sheet 3INVENTOR W Jfiowuw 4 Q TTO RNE Y6 March 28, 1939. R. THOMAS 2,152,224

MULTIPLE IMAGE OPTICAL SYSTEM Filed June 50, 1936 4 Sheets-Sheet 4INVENTOR.

ATTORNEYS Patented Mar. 28, 1939 UNITED STATES PATENT OFFICE ApplicationJune 30,

7 Claims.

This invention relates to means and methods whereby a plurality ofisomorphous photographic images may be readily obtained without theintroduction of optial errors or undue loss of light.

6 The isomorphous images may be of different color values and theresulting negatives may be used in either additive or subtractiveprocesses of color reproduction, either in motion picture photography,photolithography, or the like.

two isomorphous images could be obtained simultaneously. When a singleobjective lens and a bi-pack are used to obtain this result, the processis limited to two color work and either one or both ofthe resultingimages lack definition and detail. By using light-splitting devices,such as half silvered mirrors, etc., two separate emulsions or films canbe simultaneously exposed through a single objective but the amount oflight reaching the emulsions is materially reduced, therebynecessitating the use of higher light intensity on the scene or objector longer exposures. Furthermore, the cameras are bulky and expensive.The use of separate lenses, each supplying light to a separate film oremulsion, introduces parallax. Parallax (due to the separation of theoptical axes of the two or more lenses used) is evidenced by the factthat the resulting images are not truly insomorphous and can not besuccessfully and accurately registered. Unless perfect registration isobtained, the composite image will show fringing and be indistinct,particularly when such images are used for simultaneous projectionthrough suitable light filters upon a single observation surface.

The present invention oilers a solution to the problems and objectionsheretofore encountered. In accordance with this invention, an opticalsystem is employed which comprises a plurality of lens segments, eachlens segment containing its optical center and axis. 'I'heselenssegments are arranged with their optical axes substantially parallel,the optical axes being placed very close together. When the invention isused for 45 the production of cinematographic films, these optical axesshould be closer together, both horizontally and vertically, than thegeometric centers of the separate, full image areas to which light issupplied by the lens segments. By util- 50 izing the axial portion oflenses in this manner, errors due to spherical aberration, chromaticaberration, astigmatic error, etc., common to systems which utilize theouter portions of a lens, rather than the axial portion, are of nosignifi- 55 canoe. The complete compound lens assembly Heretofore,methods have been devised whereby 1938, Serial No. 88,151

of this invention is faster and has more light gathering capacity than asingle, normal lens of the same overall diameter.

Ordinarily, the image areas would overlap if the optical axes wereplaced as close together as 5 this invention contemplates. This problemis solved in accordance with this invention by the use of suitabledeflecting means whereby the light passing through each of the lenssegments is maintained separate and deflected away from the adjoininglens segments to an equal and predetermined extent. As a result, it ispossible to obtain a plurality of isomorphous images of the requiredsize without sacrificing normal exposure or definition, the resultingimage areas containing images of objects in identical positions andrelationships so that parallax or lack of registration is not visibleeven though the images are highly magnified during superimposition.

The invention also contemplates methods and means of reproducing objectsin substantially natural colors by the use of light filters of a kindand number more specifically described. hereinafter whereby thecharacteristics of normal panchromatic photographic emulsions areutilized to best advantage in the formation of color films of greatfidelity.

It is an object of the present invention, therefore, to disclose andprovide a method whereby a plurality of substantially isomorphousphotographic images may be simultaneously obtained without visibleparallax.

Another object is to disclose and provide a method whereby a pluralityof separated, substan tially identical images of diflerent color valuemay be obtained from a substantially identical point of view, withoutundue loss of light.

A further object of the invention is to disclose and provide a structureand a combination of elements whereby a plurality of isomorphousseparated images may be simultaneously produced for use in variousprocesses of color reproduction.

Other objects, advantages and uses of the present invention will becomeapparent to those skilled in the art from the following detailed de- 5scrlption of preferred forms of the invention, it being understood thatsuch preferred forms are described in considerable detail for thepurpose of illustration only.

In order to facilitate understanding of the invention, reference will behad to the appended drawings, in which:

Fig. 1 is a side elevation of a motion picture camera provided withelements which permit the performance of the method.

Fig. 2 is a perspective view of a segmental lens element which may beused in the optical system of this invention.

Fig. 3 is a diagrammatic isometric view illustrating the paths ofparaxial rays in the production oi the isomorphous images.

Fig. 4 is an isometric view illustrating one form 01' construction.

Figs. 5 and 6 are isometric views illustrating modified forms ofconstruction.

Fig. 'l is a longitudinal section through the optical system shown inFig. 6.

Fig. 8 is a horizontal section through a camera lens provided with themeans of this invention.

Fig. 9 is a vertical section through the camera lens of Fig. 8, thesection being taken along the plane lX-IX of Fig. 8.

Figs. 10, 11 and 12 are transverse sections taken along the planes x-x,XI-Xl' and XlIXlI of Fig. 9.

Fig. 13 is a front view of the camera lens shown in Figs. 8 and 9.

Fig. 14 is an isometric view of an optical system embodying theinventions herein described.

Fig. 15 is a vertical section through the optical system of Fig. 14,illustrating the relationship between the elements when focused atinfinity.

Figs. 16 and 17 are diagrammatic representations showing ingreaterdetail the path of light passing through one of the quadrantal lenssegments when reflecting means are-used.

Fig. 18 is a front view, partly diagrammatic, of a camera provided withthe multiple image optical system of this invention, and with means foradlustably positioning the lens segments. Fig. 19 is a section takenalong the plane XIX-XIX through a portion of Fig. 18.

As shown in Fig. 1, a form of camera provided with magazines I and 2removabiy mounted upon the camera housing 3 is provided with an opticalsystem generally indicated at 4, said optical system being adapted tofocus upon the fllm passing through the camera and simultaneously exposeadjacent areas of the film to form a plurality of isomorphous spacedimages capable of registration with one another upon superimposition,either mechanically or by projection.

The optical system embodied in the camera lens 4 may be designed tosimultaneously focus and produce three or more isomorphous spacedimages. For purpose of illustration, the optical systems hereinafterdescribed are those adapted to produce four images simultaneously. Forthis purpose, lens segments of the character illustrated in Fig. 2 areemployed, each of these lens segments subtending more than 90 of the arcof a complete lens, thereby including the optical center or optical axisof the originallens. In Fig. 2 the optical axis is indicated at 5 andthe desired segment is indicated at 6. The angle i0 is about 90'' but itis understood that when a smaller or larger number of images is to besimultaneously obtained. this angle may be either greater or smallerthan 90". Furthermore, although a single thick lens segment is shown inFig. 2, it is to be understood that a segment of similar character isformed from the compound projection or camera lens when such compoundlenses are used.

Fig. 3 diagrammatically illustrates the arrangement of the segmentallens. As there shown the lens segments 0, I, 3 and 9 are arranged withtheir optical axes close together. These optical axes should be closertogether than the geometric centers of the complete separate isomorphousimages which it is desired to obtain. The image planes and It.

or image areas on which each of the lens segments forms its image areindicated at l3, l1, l3

In order to minimize parallax to'such an extent that the images formedon areas ii to l 9 inclusive are capable of being superimposed withoutfringing or lack of definition, the optical axes of the lens segments 3to l inclusive are placed very close together. In all instances, suchoptical axes are closer together than the geometric centers of theseparated image areas. For motion picture work it has been found highlydesirable to place these optical axes about 0.30 inch apart. Even betterresults are obtained when the optical axes are closer together but inall instances each lens segment must include its true optical axis andthe sides of the segment should not pass directly through the opticalaxis.

In order to obtain separated images from an optical system includinglens segments, such as 8 to Q inclusive, the bundle of light passingthrough each lens segment is kept separate from the bundle of lightpassing through adjoining segments. Furthermore, each bundle of light isdeflected away from an adjoining bundle of light. As shown in Fig. 3,paraxial rays through the upper lens segments 6 and I are first bentupwardly as at H whereas the paraxial rays passing through the lowerlens segments 3 and 3 are bent downwardly as indicated at I2. Thereafterthe paraxial rays passing through the upper lens segments 6 and I aredirected toward the image plane as indicated at i3 and then separated bybeing oppositely deflected as indicated at I. These rays are thendirected toward the geometric centers of the image fields l0 and II, asindicated at IS, the paraxial rays passing through the lower lenssegments 3 and 9 being similarly deflected, reaching the geometricalcenters of the image frames l3 and IS.

The deflecting means may assume various forms. Refraction throughmembers provided with parallel sides or prisms may be used either aloneor in combination with suitably positioned reflecting surfaces, or suchreflecting means may be combined with refracting means.

The arrangement shown in Fig. 4 diagrammatically illustrates the use ofreflecting means only. As there shown the lens segments 3, I, 3 and 9are separated by suitable septa 20 and 2| which extend rearwardlysubstantially to a plane through which a shutter indicated at 22rotates. The path of the paraxial ray I0 is illustrated and it will beseen that it is upwardly deflected by means of a reflecting member 23,then reflected toward the image plane by the reflecting mem ber 24,subsequently reflected outwardly by the reflecting means 25 and againreflected toward the image plane by the member 23. When it is desiredthat the isomorphous images be ,of different color value, suitable lightfilters such as the filters 21, 28, etc., are positioned between theoptical system and the image plane in which the emulsion carried by thefilm is positioned. A suitable gate is indicated at 3|. Means forintermittently moving the film are not shown, it being understood thatin cinematography the film 30 will be periodically advancedlongitudinally a distance equivalent to the height of a pair ofisomorphous, simultaneously produced images, in timed relation with therotation of the shutter 22.

The reflecting means 23, 24, 25 and 23 are preferably aluminized or madesurface-reflective in any suitable manner, thereby preventing thesecondary reflections and loss of light which takes place when mirrorsare employed. Furthermore, the reflecting members 23 to 23inclusive arepreferably of progressively increasing height, the spacing betweenreflecting members of the second pair being progressively greater thanthe space between the members of the first pair. The progressivelyincreasing height and spacing of the reflecting members accommodates thegradual spread of the bundle of light passing through each of the lenssegments. The reflecting members 23, 24 and 25 lie in planes at 45 tothe optical axis Ill. The reflecting member 28 is preferably placed atsuch an angle that the angle of incidence with a paraxial ray is between45-30' and 4630. v

The height of the member 23 should be only suiilcient to gather andreflect all of that bundle of light which is supplied thereto by thesegmental lens 1. Moreover, all of the reflecting means 23 to 25inclusive should be positioned as close to the segment lens 1 aspossible but preferably between the lens and its principal focal point.The total travel of the rays through the various reflecting means (orretracting means) to the film should be equal to the focal length of thelens segments used. In the embodiment shown in Fig. 4, the entireassembly, including the lens segments and reflecting means, is movedbodily during focusing although in certain embodiments of the inventiona part, or even all, of the reflecting or refracting means may bestationary with respect to the fllm, only the lens segments movingduring focusing of the device.

The simultaneous movement of the lens segments and reflecting ordeflecting members is particularly adapted for use with lens segments ofthe wide angle type or lenses in which the adjustment for differentfocal depths (or objects at different distances from the lens) involvesan appreciable movement of the lens toward or away from the image plane.When the focusing movement of the lens is inappreciable, the lens maymove toward and away from reflecting or deflecting members, whichmembers are then stationary with respect to the image plane on which thephotographic images are to be obtained. A detailed constructionembodying the above is illustrated in Figs. 8 to 13 inclusive. As thereshown, the camera 3 is provided with a flxed iris cylinder 32, the lensbarrel 33 being slidably mounted within the iris cylinder. The iriscylinder is provided with a pair of opposing slots 34 parallel to theaxis of the cylinder whereas the lens barrel 33 is provided with a pairof pins 35 slidably extending through the slots 34 and into helicalgrooves or apertures 35 formed in a rotatable sleeve 31 carried by theiris cylinder. Rotation of the sleeve 31 can thus be translated intoaxial movement of the lens segments carried by the lens barrel 33. Theforward end of the iris cylinder 32 is provided with a suitable. irisdiaphragm, such as the diaphragm indicated at 38, this single diaphragmmodulating and stopping the light passing through the plurality of lenssegments. The iris 38 may be adjusted by means of a ring 39.

The reflecting members, such as the members 23 to 26, are firmlyattached to the member 32. The septa separating the various lenssegments and separate bundles of light may be of an extendable,overlapping type so as to positively prevent any interference betweenlight beams admitted into the camera through adjoining lens segments.

Instead of employing reflecting members. similar results may be attainedby the use of deflecting members-in the form of prisms, refractingblocks, etc. Fig. 5, for example, represents an optical system in whichlight passing through the lens segment 1 is upwardly deflected by meansof a prism 40, the light being then corrected or rendered substantiallyparallel to the optical axis by means of a prism 4|. Light upwardlydisplaced (with respect to the optical axis of the lens segment 1) bymeans of the prisms 40 and 4| may then be deflected in a directionsubstantially at right angles to the flrst deflection by means of thereflecting members 25 and 26'. The correcting prism 4| may be ofslightly greater power than the prism 40, the difl'erence being of theorder of 1 and slrflicient to make a diil'erence or not more than about0.002 inch in the position of an object point on the fllm when the lensemployed is of such character that it is subject to a travel of about-fi inch in focusing from inflnity to 6 or 8 feet.

The arrangement illustrated in Fig. '7 eliminates the use of reflectingmembers altogether. Light from the segmental lens 1 passes into arefracting block 42 provided with parallel sides whereby the bundle oflight is upwardly refracted. The light is then outwardly deflected bymeans of the prism 43. The path taken by the light rays through anarrangement such as is shown in Fig. 6, is illustrated in Fig. 7.

Fig. 14 discloses an arrangement whereby light passing through thesegmental lens 44 is upwardly deflected by a prism 45 and then outwardlydeflected by means of the prism 46. The lens segments and the prisms 45and 48 may move together and may be mounted within a barrel 41. Betweensuch optical unit and the image plane compensating prisms may bepositioned. Such compensating prisms may include a prism 44 which isoppositely angulated with respect to prism 45 and a prism 49 which isoppositely angulated with respect to the prism 45. Whenever reference ismade to prisms herein, reference is made to normal prisms provided withplane surfaces. Each prism is preferably positioned in such manner thatneither of the two plane faces lies in a plane at right angles to theoptical axis of the optical unit as a whole.

Moreover, although the prisms may vary in refracting power, prismshaving an angulation of from about 3 to 15 have been found entirelysatisfactory, the refracting power of the prism used depending somewhatupon the focal length of the lens and the desired size, contour andspacing of the flnal images. The compensating prisms, such as the prisms48 and 48, are preferably of a power equivalent to or slightly greaterthan the power of the prisms 45 and 48 respectively. The prisms as shownin the diagrammatic representations thereof are made from a plurality ofglasses for the purpose of correcting the prisms for aberration andcolor separation.

It is to be understood that all of the prisms can move with the lenssegments as shown, or the compensating prism 48 may be positionedbetween the prisms 45 and 46 and be held stationary whereas the primaryprisms 45 and 45 are movable with the lens segment 44. Those skilled inthe optical arts will appreciate that numerous changes and modificationsmay be made in the arrangement of the various prisms.

In the production of cinematographic fllms in colors, it has been foundhighly desirable to employ a'novel arrangement of color filters. It hasbeen found. for example, that the present panchromatic emulsions arevery susceptible to light of shorter wave length than blue, such as forexample, violet. In order to compensate for this unusual sensitivity ofpresent panchromatic emulsions to these short wave lengths, it has beenfound highly desirable to use a red light filter, a green light filter,and expose two frames to dense violet filters. The arrangement of colorfilters and the resulting color impressions are shown in Fig. 4. It hasbeen found necessary to use violet filters'of appreciable opacity,particularly when aluminized reflecting surfaces are used in the opticalsystem, because the short wave lengths such as violet, are apparentlyreflected by such aluminized surfaces without the loss whichcharacterizes the reflection of other wave lengths. Moreover, by the useof very dense violet filters, two partially exposed violet images areobtained and a much better color rendition is obtained in this manner.Furthermore, by obtaining two underexposed violet images, the processand the blending of the colors is more readily controlled.

The present invention is not limited to the use of the hereinabovereferred to specific arrangement of color filters since the opticalsystem of the invention may be used with light-filters of any desiredcharacter. For example, the four color filters may include red, green,violet and yellow. This arrangement is of particular value when thesubject matter being photographed contains appreciable quantities ofyellow which it is desired to emphasize. Red, green, violet and blue maybe used. Again, one of the image areas may be retained for an ordinarymonochromatic black and white image which may be used either for thepurpose of adding density to the composite or such black and white imagemay be reserved for the production of ordinary black and white releases.

When Eastman panchromatic emulsion was used, it was found that a redcolor filter similar to Wratten No. 25-A, transmitting wave lengths fromabout 580 to 700, could well be employed with a Wratten No. 58selectively transmitting wave lengths in the 480-600 range and a WrattenNo. 47 transmitting wave lengths ranging from about 350-520. When it isdesired to use a yellow filter, a filter similar to No. 6-Kl has beenfound suitable. Violet filters similar to No. 35, frequentlytransmitting wave lengths ranging from about 320 to 460, and some of thered, have also been successfully employed.

Figs. 16 and 17 diagrammatically illustrate the essentials which need befollowed in satisfactorily arranging various mirrors, when reflectingmeans are employed. It is to be noted that the mirrors 23 and 24 areplaced just as close to the lens as possible, the forward edge of themirror 24 being, as a matter of fact, more forwardly positioned than thefront edge of mirror 23. As but a very narrow beam of light is emittedby the lens, the height of the mirror 23 (indicated at h) need not bemore than one-half of the radius of the lens used. Actually this heightwill be between one-third and one-half of the radius. The mirror 24 isof slightly greater height thar the mirror 23 so that h exceeds h.Mirrors 23, 24 and 25 may be positioned so as to lie in planes at 45 tothe optical axis of the lens. The reflecting means 28, however, may bepositioned either at an angle of 45 or preferably at an angle of about46. The angulation of the last mirror generally varies from about 45-30'to about 4555'. Even larger angulations may be used for certain purposes. This increase in the angulation of the beam has the effect ofminimizing and rendering invisible what small degree of parallax isinherently present and due to the minor spacing of the optical axes ofthe quadrantal'lens segments.

In an actual case in which '75 millimeter lenses were employed for afocal length of 3 inches, the spacing between the optical axes was 0.2inch. The front element of each lens had a diameter of 1.25 inches, thelast or rear elements having a diameter of 0.75 inch. The height h ofthe first mirrors 23 was .24 inch. The distance between mirrors 23 and24 (along the paraxial ray) was 0.295 inch. The distance between mirrors25 and 26 along the paraxial ray was 0.427 inch. In that case, mirrors24 and 26 were both inclined at an angle of 4555.

In actual practice, a 65 or 70 millimeter negative film is exposed in acamera provided with an optical system of the character described hereinand the prints are then preferably made by optical reduction onto a 35millimeter film. Such 35 millimeter film is then projected through asuitable projection lens consisting of lens segments, such as the lenssegments 6, I, 8 and 9, but without the.use of the reflecting orrefracting means. The lens segments are necessarily adjustable so as toproduce a superimposed image upon the screen.

During projection, suitable color filters are introduced in the path ofthe light rays coming from each of the image Ereas so that the finishedprojected image is in substantially natural colors. In the event thenegative is to be used for photolithographic or other process work, thesteps and procedure normally followed in such photolithographic or otherprocess work are also followed in treating the negatives obtained bymeans of the optical system hereinabove described.

In order to properly center the images upon the respective rectangularframes, it may be highly desirable to adjust the lens segments, such asthe lens segments 6, I, 8 and 9, radially with respect to their commonaxis. Preferably, the adjustment of the lens segments should be along aplane passing through the diagonally related corners of the aperture orimage area. Means for accomplishing this adjustment are shown in Figs.18 and 19 but reference is made to a copending application Serial No.2,807, filed January 21, 1935, now Patent No. 2,097,706, in which oneform of device capable of being employed in obtaining such regulatableadjustment is described and claimed in detail.

As shown in Figs. 18 and 19, the lens segments 6, I, 9 and 9 may becarried by segmental holders, such as 50 and 5|, the plane sides of suchholders acting to form septa. These lens holders may be movablypositioned within a barrel 52. Attached to each lens holder andextending radially therefrom is an internally threaded socket block suchas the socket blocks 53 and 54. These socket blocks extend throughperforations in the barrel 52 and lie along the diagonals .r--::: of thepicture areas being projected. Carried by the barrel 52 is a holder 59in which there is journaled a plurality of radially arranged stems 55provided with externally threaded ends engaging the internally threadedsocket blocks 33. The stems 55 carry pinions 59. The pinions in turnengage a ring gear 51 which may be rotatably mounted upon the barrel I2and which may be locked in any desired position as by means of setscrews 58. It will be evident that rotation of the ring gear 51 willrotate the pinions 56 and thereby, cause the threaded stems to move theinternally threaded socket blocks 53, thereby imparting motion to thelens holders 50, 5|, etc. along lines which coincide with the diagonalaxes of the picture areas which are being projected.

I claim:

1. A photographic optical system whereby a plurality of images of ascene may be obtained simultaneously without visible parallax,comprising: four segmental optical units arranged about a common axisparallel to the optical axes of said units, each of said units includingan objective lens segment containing the optical center thereof, theobjective lens segments being arranged with their optical centers closertogether than the geometrical centers of image areas in an image plane;means for deflecting light from each of said objective lens segments ina direction away from an adjoining optical unit; compensating reflectiveplane means adapted to direct deflected light onto desired image areas,said compensating means being stationary with respect to the image planeand lying at an angle of more than to the optical axis; shutter meansoperably positioned between said deflecting means and the image plane;septum means separating said segmental units; and color filterspositioned between said optical units and the image plane whereby imagesof complementary color value can be simultaneously recorded.

2. An optical system including: four segmental optical units arrangedabout a common axis parallel to the optical axes of said units, each ofsaid units including an objective lens segment containing the opticalcenter thereof, and planes provided with reflecting surfaces adapted todirect light from said lens units toward separated image areas on asingle film, a series of said planes acting upon light from eacPof saidunits, the planes of each series being of progressively increasing size,the front planes of each series being adapted to reflect light from saidlens units in directions lying in parallel planes, two of said frontplanes reflecting their incident light in one direction and the othertwo front planes reflecting their incident light in an oppositedirection.

3. An optical system of the character stated in claim 2 in which therear planes of each series are positioned a distance farther apart,along the path of axial rays, than the front planes.

4. An optical system of the character described in claim 2 in which thelast plane of each series is at an angle of slightly more than 45 to theoptical axis.

5. An optical system of the character described in claim 2 in which therear planes of each series are farther apart, along the path of axialrays, than the front planes, the last plane of each series being at anangle of slightly more than 45 to the optical axis, said optical systembeing spaced with respect to the image plane so that the total travel oflight rays from the nodal point of lens units to the image plane isequal to the focal length of the lens unit.

6. In an optical system whereby a plurality of separate images may besimultaneously exposed upon a film, the combination of four quadrantallens systems, each including its optical axis, said four systems beingpositioned with their optical axes substantially parallel and closertogether than the geometric centers of the image areas on which theimages are to be exposed; means for deflecting light from each of saidquadrantal lens systems in a direction away from an adjoining lenssystem, means for directing said deflected light onto a desired imagearea, a color filter selectively transmitting red wave lengthspositioned in the path of light from one of said lens systems, a colorfilter selectively transmitting green wave lengths positioned in thepath of light from another lens system, and color filters transmittingviolet positioned in the path of light p assing through the remainingtwo lens systems.

7. A photographic optical system whereby a plurality of images of ascene may be obtained simultaneously without visible parallax,comprising: a plurality of segmental optical units arranged about acommon axis parallel to the optical axes of said units, each of saidunits including an objective lens segment containing the optical centerthereof, the objective lens segments being arranged with their opticalcenters closer together than the geometrical centers of image areas inan image plane; means for deflecting light from each of said objectivelens segments in a direction away from an adjoining optical unit; septummeans separating said segmental units; and means for adjusting saidsegmental units radially.

RICHARD THOMAS.

